Sada*, if you have never purchased anything online with your debit card before, why not give it a try beforehand with something small and unimportant, and that way you won't have anything to worry about when the day approaches?
I have purchased things online before but through PayPal. I recently updated my card to a debit credit card but the bank explained that I can only pay directly with the card if the seller has debit credit card options not just credit cards.
I might do the prepaid visa card idea. It seems like the simplest.
@Swtess I'm from Ottawa so I'm planning on an Ottawa to Montreal then NYC trip. Where will you be travelling from?
I had a prepaid visa before and tried purchasing something online and it didn't work. I only use a debit card for every online transaction I make (or PayPal which is directly attached to my debit). It works fine; no worries.